From a8a977e25f90cd39feab10ff37f92c274d9dba2c Mon Sep 17 00:00:00 2001
From: Art Chaidarun <artchaidarun@gmail.com>
Date: Sat, 26 Jun 2021 03:08:16 -0400
Subject: [PATCH] Format R

---
 Dockerfile | 16 ++++++++++------
 README.md  |  1 +
 entry.ts   | 31 +++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index 853bca8..88470c8 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,18 +1,22 @@
 FROM alpine:3.12.1
 
-# Alpine base packages
+# Alpine packages
 RUN apk update && apk upgrade && apk add --no-cache \
   bash \
   build-base \
+  clang \
   git \
   nodejs-npm \
   openjdk11 \
   py3-pip \
-  python3-dev
+  python3-dev \
+  R \
+  R-dev
 
-# Alpine tool packages
-RUN apk update && apk upgrade && apk add --no-cache \
-  clang
+# R packages
+RUN Rscript -e '\
+    install.packages("remotes", repos = "https://cloud.r-project.org"); \
+    remotes::install_github("r-lib/styler@v1.4.1", Ncpus = 8)'
 
 # Python packages
 RUN pip3 install --upgrade pip && pip3 install \
@@ -34,7 +38,7 @@ RUN wget https://releases.hashicorp.com/terraform/0.11.14/terraform_0.11.14_linu
 
 # Scala packages
 RUN wget https://github.com/coursier/coursier/releases/download/v2.0.6/coursier -O /bin/coursier \
-    && chmod +x /bin/coursier
+  && chmod +x /bin/coursier
 RUN coursier bootstrap org.scalameta:scalafmt-cli_2.13:2.7.5 \
       -r sonatype:snapshots --main org.scalafmt.cli.Cli \
       --standalone \
diff --git a/README.md b/README.md
index 904ea39..f5d729b 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,7 @@ This repo currently contains a single [pre-commit](https://pre-commit.com/) hook
 - [ktfmt](https://github.com/facebookincubator/ktfmt) v0.25 for Kotlin
 - [scalafmt](https://scalameta.org/scalafmt/) v2.7.5 for Scala
 - [shfmt](https://github.com/mvdan/sh) v3.2.0 for Shell
+- [styler](https://github.com/r-lib/styler) v1.4.1 for R
 - [terraform fmt](https://github.com/hashicorp/terraform) v0.11.14 and v0.12.29 for Terraform
 - [ClangFormat](https://clang.llvm.org/docs/ClangFormat.html) v10.0.0 for Protobuf
 - [SVGO](https://github.com/svg/svgo) v1.3.2 for SVG
diff --git a/entry.ts b/entry.ts
index 06da69d..722aaca 100644
--- a/entry.ts
+++ b/entry.ts
@@ -76,6 +76,7 @@ const enum HookName {
   Scalafmt = "scalafmt",
   Sed = "sed",
   Shfmt = "shfmt",
+  Styler = "styler",
   Svgo = "SVGO",
   TerraformFmt = "terraform fmt",
 }
@@ -310,6 +311,36 @@ const HOOKS: Record<HookName, LockableHook> = {
     include: /./,
     runAfter: [HookName.Sed],
   }),
+  [HookName.Styler]: createLockableHook({
+    action: async sources => {
+      const output = await run(
+        "Rscript",
+        "-e",
+        // We need to set `R.cache.rootPath` ourselves because otherwise Styler
+        // fails (but only when actually run via pre-commit, not when tested
+        // directly in a `docker run [...] bash` terminal?!) with this error:
+        //
+        // When processing foobar.r: .onLoad failed in loadNamespace
+        // () for 'R.cache', details:
+        //   call: mkdirs.default(parent, mustWork = mustWork, maxTries =
+        //   maxTries,
+        //   error: Failed to create directory (tried 5 times), most likely
+        //   because of lack of file permissions (directory '/' exists but
+        //   nothing beyond): //.cache
+        `options(R.cache.rootPath = "/tmp/rcache");${sources
+          .map(s => `styler::style_file("${s}", scope = "line_breaks")`)
+          .join(";")}`,
+      );
+
+      // R doesn't exit with nonzero code upon failure, so we have to detect
+      // failure ourselves :/
+      if (!/\s0\s+Styling threw an error/.test(output)) {
+        throw output;
+      }
+    },
+    include: /\.(R|Rmd|Rnw|Rprofile)$/i,
+    runAfter: [HookName.Sed],
+  }),
   [HookName.Svgo]: createLockableHook({
     action: sources =>
       run(